As transmission belts, friction driving transmission belts such as a V belt and a V-ribbed belt, and other belts are known. These are widely used for automobiles, general industries, and others.
The transmission belts each have, for example, a rubber coat canvas for covering the surface, an adhesive rubber layer in which core lines such as filaments are embedded, and a compression rubber layer laminated on the adhesive rubber layer, and are each made mainly of a rubber composition.
In this sort of transmission belt, the following has widely been used hitherto as the rubber component of the rubber composition from the viewpoint of restraining a remarkable deterioration of the rubber in a high-temperature atmosphere and improving the softness of the rubber in a low-temperature atmosphere: natural rubber (NR), styrene/butadiene copolymer rubber (SBR), chloroprene rubber (CR), ethylene/α-olefin copolymer rubber, hydrogenated nitrile-butadiene rubber (H-NBR), alkylated chlorosulfonated polyethylene (ACSM), or the like.
In particular, ethylene/α-olefin copolymer rubber is relatively frequently used since the rubber is better in heat resistance and cold resistance than chloroprene rubber (for example, Patent Document 1).
However, conventional ethylene/α-olefin copolymer rubber is easily worn away; thus, the rubber has an aspect that the lifespan is shorter than that of chloroprene rubber. Furthermore, the transmission belt made of ethylene/α-olefin copolymer rubber has an aspect that the belt is lacking in softness in a driving test under a severe condition of a low temperature such as −40° C., and in other situations.
As described above, conventional transmission belts have problems that the belts are easily worn away and are not yet sufficient in softness in a low-temperature atmosphere.
Patent Document 1: JP-A-9-176402